Traditionally, bags having capacities of between about 50 pounds and about 100 pounds have been used to receive, transport, store, and discharge dry flowable solids such as minerals and chemicals, foodstuffs, etc. More recently, flexible intermediate bulk containers, commonly referred to as bulk bags, have come into widespread use for receiving, transporting, storing, and discharging dry flowable solids and other materials. Although numerous bulk bag designs are known, most bulk bags are adapted to receive materials through the top and to discharge the previously received materials through the bottom of the bulk bag.
In certain industries large boxes are utilized in the handling of dry flowable solids. In use, the boxes are received in machinery which functions to tip the boxes upside down to effect rapid discharge of the contents therefrom. Although generally satisfactory, the use of boxes in the handling of dry flowable solids involves certain disadvantages. For example, boxes are generally not adapted to be folded for transport. Additionally, the cleaning and recycling of boxes utilized in the handling of dry flowable solids can be problematic.
U.S. Pat. No. 4,903,859 discloses a bulk bag comprising four double layer side walls. Stiffeners formed from cardboard are inserted between the layers of the side walls thereby imparting sufficient rigidity to the container to permit its use with liquids. Although the bulk bag of the '859 patent has been generally well received, its utilization has been somewhat limited by the fact that it cannot be stacked.
Co-pending application Ser. No. 09/390,403 assigned to the assignee hereof (doing business as Composite Container Corp.) discloses an improvement over the bulk bag of the '859 patent. In application Ser. No. 09/390,403 there is disclosed a bulk bag having double layer side walls and vertically extending corner pockets. Plywood sheets are received between the layers of the side walls and wooden posts are received in the corner pockets to provide a bulk bag suitable for use with liquids which is stackable.
U.S. Pat. No. 5,076,710 discloses a baffle-type bulk bag wherein bridge panels or baffles are sewn across the four corners of a nominally rectangular bulk bag. The baffles prevent the side walls of the bulk bags from bulging outwardly when the bulk bag is filled, thereby retaining the filled bulk bag in a more or less rectangular cross-sectional configuration. The baffles may be provided with apertures which allow material to flow into and out of the corners of the bulk bag during filling and discharging operations.
The present invention comprises a bulk bag which adapts the technologies of the '859 and '710 patents and the '403 application to provide a bulk bag which functions as a replacement for the material handling boxes described hereinabove. The bulk bags of the present invention incorporate numerous advantages over the prior art material handling boxes. A primary advantage involves the fact that the bulk bags of the present invention are adapted to be folded flat for transport from the location at which the bags are manufactured to the location at which the bags are used, and for return transport from the location at which the bags are emptied to the location at which the bags are filled. Another advantage arising from the use of the invention involves the fact that the bulk bags of the present invention are adapted for cleaning and recycling.